Adjustable load wheel

ABSTRACT

A load wheel assembly for a pallet truck includes a first load arm that rotates about an axis of rotation, and a load wheel rotationally coupled to an end of the first load arm opposite from the axis of rotation. The load wheel supports a fork at an elevation above the load wheel. Additionally, the load wheel assembly includes a second load arm pivotally coupled to the first load arm at the axis of rotation and forming a load arm angle, and an adjustment mechanism further coupling the second load arm to the first load arm. The adjustment mechanism varies the load arm angle formed between the first load arm and the second load arm to adjust the elevation of the fork above the load wheel.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. provisional application No.62/467,038, entitled “ADJUSTABLE LOAD WHEEL” and filed on Mar. 3, 2017,the contents of which is incorporated in its entirety herein byreference.

TECHNICAL FIELD

Embodiments relate to the field of material handling vehicles, such aspallet trucks

BACKGROUND

Industrial vehicles such as forklift trucks, end-riders, center-riders,pallet trucks, walkies, and the like, may include a pair of forksconfigured to engage a pallet. The pallet may include one or moreopenings into which the forks are inserted prior to moving the pallet,and each opening may include upper and lower surfaces that providestability to the pallet. For example, the upper surface and/or the lowersurface of each opening may include one or more boards extending thewidth of the pallet. The forks may be inserted between the upper surfaceand the lower surface. An empty pallet may tend to slide across thefloor during insertion of the forks into the opening(s) when one of theforks contacts the upper surface and/or the lower surface of the pallet,such as when the height of the forks is uneven.

Certain types of industrial vehicles, such as pallet trucks with fixedlinkages for raising and lowering the forks, are known to have unevenfork heights and/or non-level fork surfaces due to manufacturingtolerances that may cause one fork to be either higher or lower relativeto the other. The non-level forks may result in uneven lifting andlowering, and vehicles having non-level forks may tend to rock back andforth or transfer weight between the forks, such that only one loadwheel may be in contact with the ground at any point in time. Theeffects of the uneven forks may be more pronounced when there is no loadon the forks.

While fixed linkage fork elevation systems may be relativelyuncomplicated and include a small number of component parts, thesesystems may be susceptible to tolerance stack up between the components,which may result in non-level fork surfaces. Additionally, componentssuch as pull rods and other linkage components may require specificmodel matching to limit manufacturing error, which may complicateservice and maintenance operations due to the part matchingrequirements. In some instances, a manufacturer may expend time andresources either straightening or bending the structure to get the forksto lie more evenly on the load wheels.

Some known pallet trucks have attempted to provide for adjustment of thefork height by varying the length of a pull rod. For example, anadjustment mechanism is described in U.S. Pat. No. 7,191,872 as beinglocated at the rear of the pull rod, next to the truck frame. However,these types of known adjustment mechanisms may create bending and/ortensile forces on the pull rod as a result of the adjustment process andensuing usage of the forks at the adjusted pull rod length, which canlead to premature failure or require additional maintenance beperformed. Additionally, known adjustment mechanisms located at the rearof the pull rod typically are only accessible from underneath the forks,which may require that the forks and/or entire pallet truck be raisedoff the ground a sufficient distance to provide user access.

SUMMARY

A load wheel assembly for a pallet truck is disclosed herein. The loadwheel assembly may include a first load arm that rotates about an axisof rotation, and a load wheel rotationally coupled to an end of thefirst load arm opposite from the axis of rotation. The load wheel maysupport a fork at an elevation above the load wheel. Additionally, theload wheel assembly may include a second load arm pivotally coupled tothe first load arm at the axis of rotation and forming a load arm angle,and an adjustment mechanism further coupling the second load arm to thefirst load arm. The adjustment mechanism may vary the load arm angleformed between the first load arm and the second load arm to adjust theelevation of the fork above the load wheel.

In some examples, the adjustment mechanism may adjust a height of thefirst load wheel relative to the operating surface without changing theelevation of the first fork. Additionally, the adjustment mechanism mayadjust a distance between the first load wheel and the first forkwithout changing the elevation of the first fork

An example method is disclosed herein. The method may include locating apallet truck on a flat operating surface. The pallet truck may include afirst fork and a second fork, and an elevation of the first forkrelative to the operating surface may be different than a secondelevation of the second fork relative to the operating surface. Themethod may further include pulling a first pull rod to raise the firstfork from a lowered position to a raised position, and pulling a secondpull rod to raise the second fork from a second lowered position to asecond raised position. Via an adjustment mechanism operably coupled toboth the first pull rod and a first load wheel at least partially housedwithin the first fork, a height of the first load wheel may be adjustedrelative to the operating surface without changing the elevation of thefirst fork. In some example methods, a distance between the first loadwheel and the first fork may be adjusted without changing the elevationof the first fork.

Additionally, a number of apparatus and systems are disclosed herein,including means for performing the example methods.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. Embodimentsare illustrated by way of example and not by way of limitation in thefigures of the accompanying drawings.

FIG. 1 illustrates an example pallet truck being controlled by anoperator, in accordance with various embodiments;

FIG. 2 illustrates an example pallet truck with a pair of forks locatedin a raised position, in accordance with various embodiments;

FIG. 3 illustrates a partial view of the example pallet truck of FIG. 2,with the forks being inserted into a pallet, in accordance with variousembodiments;

FIG. 4 illustrates an embodiment of an adjustable load wheel assemblythat includes a fixed linkage system, in accordance with variousembodiments;

FIG. 5 illustrates another embodiment of an adjustable load wheelassembly that includes an adjustable linkage system, in accordance withvarious embodiments;

FIG. 6 illustrates an enlarged isometric view of the adjustable loadwheel assembly of FIG. 5; in accordance with various embodiments;

FIG. 6A illustrates a side view of the adjustable load wheel assembly ofFIG. 6, shown in isolation from the fork, in accordance with variousembodiments;

FIG. 7 illustrates an exploded view of the adjustable load wheelassembly of FIG. 6, in accordance with various embodiments;

FIG. 8 illustrates a cross-sectional view of an embodiment of anadjustable load wheel assembly including a rotational adjustment device,in accordance with various embodiments;

FIG. 9A illustrates a bottom view of the adjustable load wheel assemblyof FIG. 8, in accordance with various embodiments;

FIG. 9B illustrates an elevated side view of the adjustable load wheelassembly of FIG. 8, in accordance with various embodiments;

FIG. 10A illustrates a perspective view of another embodiment of anadjustable load wheel assembly, in accordance with various embodiments;

FIG. 10B illustrates a top view of the adjustable load wheel assembly ofFIG. 10A, in accordance with various embodiments;

FIG. 10C illustrates a side view of the adjustable load wheel assemblyof FIG. 10A, in accordance with various embodiments;

FIG. 10D illustrates an exploded view of the example load wheel assemblyof FIG. 10A, in accordance with various embodiments;

FIG. 11A illustrates a perspective view of another embodiment of anadjustable load wheel assembly, in accordance with various embodiments;

FIG. 11B illustrates a top view of the adjustable load wheel assembly ofFIG. 11A, in accordance with various embodiments;

FIG. 11C illustrates a side view of the adjustable load wheel assemblyof FIG. 10A, in accordance with various embodiments;

FIG. 11D illustrates an exploded view of the adjustable load wheelassembly of FIG. 11A, in accordance with various embodiments; and

FIG. 12 illustrates an example process of operating an adjustable loadwheel assembly that includes an adjustable linkage system, in accordancewith various embodiments.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which are shownby way of illustration embodiments that may be practiced. It is to beunderstood that other embodiments may be utilized and structural orlogical changes may be made without departing from the scope. Therefore,the following detailed description is not to be taken in a limitingsense, and the scope of embodiments is defined by the appended claimsand their equivalents.

Various operations may be described as multiple discrete operations inturn, in a manner that may be helpful in understanding embodiments;however, the order of description should not be construed to imply thatthese operations are order dependent.

The description may use perspective-based descriptions such as up/down,back/front, and top/bottom. Such descriptions are merely used tofacilitate the discussion and are not intended to restrict theapplication of disclosed embodiments.

The terms “coupled” and “connected,” along with their derivatives, maybe used. It should be understood that these terms are not intended assynonyms for each other. Rather, in particular embodiments, “connected”may be used to indicate that two or more elements are in direct physicalor electrical contact with each other. “Coupled” may mean that two ormore elements are in direct physical or electrical contact. However,“coupled” may also mean that two or more elements are not in directcontact with each other, but yet still cooperate or interact with eachother.

For the purposes of the description, a phrase in the form “A/B” or inthe form “A and/or B” means (A), (B), or (A and B). For the purposes ofthe description, a phrase in the form “at least one of A, B, and C”means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).For the purposes of the description, a phrase in the form “(A)B” means(B) or (AB) that is, A is an optional element.

The description may use the terms “embodiment” or “embodiments,” whichmay each refer to one or more of the same or different embodiments.Furthermore, the terms “comprising,” “including,” “having,” and thelike, as used with respect to embodiments, are synonymous.

Embodiments herein provide load wheel assemblies for pallet trucks. Invarious embodiments the disclosed load wheel assemblies may include afirst load arm that rotates about an axis of rotation, and a load wheelrotationally coupled to an end of the first load arm opposite from theaxis of rotation. In various embodiments, the load wheel may support afork at an elevation above the load wheel, and in some embodiments, theload wheel assembly may include a second load arm pivotally coupled tothe first load arm at the axis of rotation and forming a load arm angle,and an adjustment mechanism further coupling the second load arm to thefirst load arm. In particular embodiments, the adjustment mechanism mayvary the load arm angle formed between the first load arm and the secondload arm to adjust the elevation of the fork above the load wheel.

In some embodiments, the adjustment mechanism may adjust a height of thefirst load wheel relative to the operating surface without changing theelevation of the first fork. Furthermore, in some embodiments, theadjustment mechanism may adjust a distance between the first load wheeland the first fork without changing the elevation of the first fork

Also disclosed are exemplary methods of using the disclosed load wheelassemblies. In some embodiments, the method may include locating apallet truck on a flat operating surface. In some example, the pallettruck may include a first fork and a second fork, and an elevation ofthe first fork relative to the operating surface may be different than asecond elevation of the second fork relative to the operating surface.In various embodiments, the method may further include pulling a firstpull rod to raise the first fork from a lowered position to a raisedposition, and pulling a second pull rod to raise the second fork from asecond lowered position to a second raised position. Via an adjustmentmechanism operably coupled to both the first pull rod and a first loadwheel at least partially housed within the first fork, a height of thefirst load wheel may be adjusted relative to the operating surfacewithout changing the elevation of the first fork. In some examples, adistance between the first load wheel and the first fork may be adjustedwithout changing the elevation of the first fork.

Additionally, a number of apparatus and systems are disclosed herein,including means for performing the example methods.

Turning now to the figures, FIG. 1 illustrates an example pallet truck100 being controlled by an operator 80. The pallet truck 100 includes asteering control device 20 to command or control various operationsassociated with the pallet truck 100, such as steering, braking,accelerating, hoisting, lowering, other types of vehicle operations, orany combination thereof. In various embodiments, the steering controldevice 20 may operate the pallet truck 100 through a mechanical linkage,a mechanical connection, one or more electrical signals, one or morewireless communications, or via a drive-by-wire system. In someembodiments, the pallet truck 100 may include motorized traction controlso as to provide for a motorized vehicle.

The pallet truck 100 is shown as including forks 30 having one or moreload wheels 40 and/or load rollers. In some embodiments, forks 30 may besupported by additional load wheels and/or load rollers such as a secondload wheel 42. A load, such as one or more pallets, may be placed on theforks 30 during transportation. In some embodiments, a load backrest 35may be attached to the forks 30 to provide lateral support for the load.

In the illustrated example, the pallet truck 100 is further shown asincluding a mounting structure or frame 60 for mounting the steeringcontrol device 20. The mounting structure 60 may be attached to thepallet truck 100 and may include a compartment for housing a tractionmotor for providing traction control of one or more drive wheels 50.

In some embodiments, the drive wheel 50 may primarily support the weightof the frame 60 and associated components. The load wheels 40, on theother hand, may be understood to primarily support the weight of theforks 30 and, when the pallet truck 100 is transporting a load, loadwheels 40 may additionally support the weight of the load. In either theladen or unladen operating condition, both the drive wheel 50 and theload wheels 40 may be in contact with a transport surface 90, such asthe floor of a warehouse or other operating surface.

FIG. 2 illustrates an example pallet truck 200 with a first fork 210 anda second fork 220 located in a raised or elevated position. The pallettruck 200 may be motorized and may include one or more drive wheels 250,one or more casters 255, and one or more load wheels, such as a firstload wheel 241 associated with first fork 210 and a second load wheel242 associated with second fork 220. In some embodiments, the load wheel241 and/or 242 may include rollers, tires, casters, or any combinationthereof, that allow the forks 210, 220 to be positioned relative to thepallet and, ultimately, to transport the pallet from one location to thenext.

First fork 210 is illustrated as including a fork tip 215. The fork tip215 may be an integrated part of the first fork 210, e.g., manufacturedtogether during a fabrication process, or may be attached to the ends offirst fork 210, e.g., during assembly or as an aftermarket service. Insome embodiments, first load wheel 241 may be located proximate to thefork tip 215 and may be raised and lowered with respect to the firstfork 210. Similarly, the height of the first fork 210 and the secondfork 220 may be increased or decreased relative to the ground when theload wheels 241, 242 are lowered or raised, respectively.

FIG. 3 illustrates the pair of forks 210, 220 from FIG. 2, preparing toengage a pallet 300. The first fork 210 may include a first fork tip215, as previously described, and the second fork 220 may include asecond fork tip 225. The pallet 300 may be a conventional pallet madeout of plastic or wood boards or planks; however, other types of palletsare also contemplated herein, including Grocery Manufacturers'Association (GMA) pallets, “Bottler's” pallets, Commonwealth HandlingEquipment Pool (CHEP) “Blue” pallets, or the like.

In various embodiments, pallet 300 may include an upper portion 320 anda lower portion 340. The upper portion 320 and the lower portion 340 mayform one or more openings in the pallet 300, including a first opening350 and a second opening 355, into which the first fork 210 and thesecond fork 220, respectively, may be inserted. The pallet 300 may beempty or loaded. When the pallet 300 is empty, it may weigh considerablyless than the forks 210, 220, such that one of the forks 210, 220 maytend to push or slide the pallet 300 across the floor when the fork tips215, 225 are inserted into the openings 350, particularly if the forks210, 220 are non-level or are associated with different heights.

For example, while first fork 215 may be located at the proper height toenter first opening 350, if the second fork 220 is at a higher positionrelative to the first fork 210, the second fork tip 225 may at leastpartially contact the upper portion 320 of the pallet. On the otherhand, the second fork 220 is at a lower position as compared to thefirst fork, the second fork tip 225 may at least partially contact thelower portion 340 of the pallet 300. The tendency to push the pallet 300may be augmented when the floor is smooth, wet, or is otherwiseassociated with a relatively low coefficient of friction.

FIG. 4 illustrates an example fork and load wheel system 400 thatincludes a fixed linkage system 450. A load wheel 440 is shown as beingat least partially housed within a fork 410 and proximate to a fork tip415. In some embodiments, the load wheel 440 may be pivotally coupled tothe fork 410. The linkage system 450 may operably couple the load wheel440 to a pull lever 460 located at an opposite end of the fork 410 fromthe fork tip 415. By pulling the pull lever 460, the fork 410 may beraised relative to the ground as the load wheel 440 pivots in a downwardmotion relative to the fork 410. On the other hand, by releasing thepull lever with the fork 410 in the raised position, the fork 410 may belowered to the ground as the load wheel 440 pivots in an upward motionrelative to the fork 410.

FIG. 5 illustrates an example fork and load wheel system 500 thatincludes an adjustable linkage system 550. The fork and load wheelsystem 500 may be configured somewhat similarly as the fork and loadwheel system 400 of FIG. 4, in that a load wheel 540 may be at leastpartially housed within a fork 510 (partially shown) and proximate to afork tip 515. Additionally, the load wheel 540 may be pivotally coupledto the fork 510, and the linkage system 550 may operably couple the loadwheel 540 to a pull attachment 560 located at an opposite end of thefork 510 from the fork tip 515 so that the fork 510 may be raised andlowered relative to the ground as the load wheel 540 pivots in adownward and upward motion, respectively, relative to the fork 510

FIG. 6 illustrates an enlarged isometric view of the example fork andload wheel system 500 of FIG. 5 including a load wheel assembly 600. Theload wheel assembly 600 may be understood to operably couple the loadwheel 540 to the fork 510. Additionally, the load wheel assembly 600 maybe understood to operably couple a pull rod 555 to the load wheel 540.In a lowered position, the load wheel 540 may be understood to be atleast partially housed within the fork 510 proximate to the fork tip515. An adjustment mechanism 570 may be understood to variably adjustthe position of the load wheel 540 relative to the fork 510.

For a pallet truck located on a flat operating surface, the pallet truckmay include a first fork, such as fork 510, and a second fork. A firstload wheel, such as load wheel 540, may be at least partially housedwithin the first fork. \Additionally, a second load wheel may be atleast partially housed within the second fork, and an elevation of thefirst fork relative to the operating surface may be different than asecond elevation of the second fork relative to the operating surface.In some embodiments, pulling a first pull rod, such as pull rod 555, mayoperate to raise the first fork from a lowered position to a raisedposition relative to the operating surface. Similarly, pulling a secondpull rod may operate to raise the second fork from a second loweredposition to a second raised position relative to the operating surface.In some examples, adjustment mechanism 570 may adjust a verticaldistance between the load wheel 540 and the fork 510 without changingthe elevation of the fork 510 relative to the operating surface.

FIG. 6A illustrates a side view of the example load wheel assembly 600of FIG. 6 shown in isolation from the fork. The load wheel assembly 600may include a first load arm 610 pivotably coupled to a second load arm640 at a fork mounting pivot 630. The fork mounting pivot 630 mayprovide an axis of rotation for the entire load wheel assembly 600relative to the fork 510 (FIG. 6).

The first load arm 610 may rotate about the axis of rotation formed byfork mounting pin 630, and the load wheel 540 may be rotationallycoupled to an end of the first load arm 610 opposite from the axis ofrotation. For example, the load wheel 540 may be rotationally coupled tothe first load arm 610 at a load wheel axis 545. The load wheel 540 maysupport the fork at an elevation above the load wheel 540. In someembodiments, the first load arm 610 may be associated with a first angleof incidence 615 that passes through the centerlines of the forkmounting pin 630 and the load wheel axis 545.

The second load arm 640 may be pivotally coupled to the first load arm610 at the axis of rotation formed by the fork mounting pin 630. In someembodiments, the second load arm 640 may be associated with a secondangle of incidence 645 that passes through the centerlines of the forkmounting pin 630 and a pull rod pin 650. Additionally, a load arm angle655 may be understood as being formed between the first angle ofincidence 615 associated with the first load arm 610 and the secondangle of incidence 645 associated with the second load arm 640, and asillustrated in the simplified diagram of FIG. 6A located above theexample load wheel assembly 600.

In some embodiments, the pull rod 555 (FIG. 6) may be pivotally coupledto the second load arm 640 at the pull rod pin 650. In some examplemodes of operation, pull rod 555 may change the elevation of the fork510 (FIG. 6) above the load wheel 540 without varying the load arm angle655.

FIG. 7 illustrates an exploded view of an example load wheel assembly ofFIG. 6. The mounting pin 630 may be understood as providing an axis ofrotation that passes through one or more aligned connection holes 635formed in the first load arm 610 and through one or more connectionholes 642 formed in the second load arm 640. The mounting pin 630 maypivotally couple the load wheel assembly 600 to the fork.

The adjustment mechanism 570 may be understood as coupling the secondload arm 640 to the first load arm 610. Additionally, the adjustmentmechanism 570 may vary the load arm angle 655 (FIG. 6A) formed betweenthe first load arm 610 and the second load arm 640 to adjust theelevation of the fork above the load wheel 540. For example, theadjustment mechanism 570 may include a threaded shaft 670, in which arotation of the threaded shaft 670 may operate to vary the load armangle 655.

The adjustment mechanism 570 may include an attachment pin 620 coupledto the first load arm 610. In some embodiments, the first load arm 610may include a pair of load arms 610, 612 between which the load wheel540 may be mounted. The attachment pin 620 may be inserted into one ormore through-holes 625 formed in the first load arm(s) 610, 612. Thethreaded shaft 670 may operably couple the attachment pin 620 to thesecond load arm 640. In some embodiments, the attachment pin 620 may becoupled to the first load arm 610 at a position intermediate the loadwheel 540 and the axis of rotation formed by the mounting pin 630.Additionally, the attachment pin 620 may include a through-hole 622centrally located in the attachment pin 620 into which the threadedshaft 670 may be inserted.

The adjustment mechanism 570 may further include an adjustable mountingstructure 660 pivotally coupled to the pull rod pin 650. Additionally,the pull rod 555 (FIG, 6) may be pivotally coupled to the second loadarm 640 by the pull rod pin 650. In some embodiments, the adjustablemounting structure 660 may be pivotally coupled to an end of the secondload arm 640 opposite the axis of rotation provided by mounting pin 630,which passes through connection hole(s) 642.

The adjustable mounting structure 660 may include a through-hole 675into which the threaded shaft 670 may be variably inserted to vary theload arm angle 655 (FIG. 6A). Additionally, the adjustment mechanism 570may further include a threaded adjustment nut 680 that maintains aninsertion depth of the threaded shaft 670 into the through-hole 675after the elevation of the fork above the load wheel 540 has beenadjusted. In some embodiments, the threaded shaft 670 may be insertedinto the attachment pin 620 prior to attaching the threaded adjustmentnut 680 to the threaded shaft 670.

FIG. 8 illustrates a cross-sectional view of an example load wheelassembly 700 including a rotational adjustment device 770. Therotational adjustment device 770 may include a threaded shaft 670. Insome embodiments, a rotation 810 of the threaded shaft 670 in a firstdirection may cause the load wheel 540 to be lowered 830 relative to thefork. Similarly, the rotation of the threaded shaft 670 in a seconddirection may operate to raise 820 the load wheel 540 relative to thefork.

In some examples, the rotational adjustment device 770 may includethreaded nut 680. Additionally, adjustable mounting structure 660 mayinclude the threaded shaft 670 variably inserted into a through-hole ofthe threaded nut 680. The insertion depth of the threaded shaft into thethrough-hole may be secured with the threaded nut 680, after the heightof the load wheel 540 relative to the operating surface is adjusted,e.g., by raising 820 or lowering 830 the load wheel 540. Additionally,the rotational adjustment device 770 may be understood to vary thedistance between the pull rod pin 650 and the load wheel 540.

In some embodiments, the height of the load wheel 540 may be adjusted byvarying the angle between the first load arm 610 and the second load arm640. The height of the load wheel 540 may be adjusted without rotatingthe entire load wheel assembly 700 about the axis of rotation providedby mounting pin 630.

The adjustable load wheel assembly 700 may be used to adjust an unevenfork relative to the ground or operating surface. In some embodiments,the adjustable load wheel assembly 700 may be understood toindependently adjust the load wheel attitude/elevation in order toreduce or eliminate any rocking or settling of the forks and/or loadwheels. Still further, the adjustable load wheel assembly 700 may beunderstood to independently adjust the load wheel attitude/elevation inorder to reduce or eliminate the effects of uneven wear that may existon the load wheels.

FIG. 9A illustrates a bottom view of the example load wheel assembly 700of FIG. 8. The ends of mounting pin 630 may be seen to extend outside ofthe first load arm 610 for mounting to the fork. In this view, it may beclearly seen that the threaded shaft 670 may be used to vary therotational orientation of the load wheel 540 and the first load arm 610relative to the mounting pin 630, while the pull rod pin 650 and thesecond load arm 640 may remain rotationally fixed with respect to themounting pin 630.

FIG. 9B illustrates an elevated side view of the example load wheelassembly 700 of FIG. 8. In this view, it can be clearly seen thatmounting pin 630 passes through both of the first load arm 610 and thesecond load arm 640 to provide a common axis of rotation, such as whenthe pull rod is activated to lower the load wheel 540.

FIGS. 10A-D illustrate several views of another embodiment of anadjustable load wheel assembly, including a perspective view (FIG. 10A),a top view (FIG. 10B), and side view (FIG. 10C), and an exploded view(FIG. 10D), in accordance with various embodiments. The load wheelassembly 800 may include a first load arm 810 pivotably coupled to asecond load arm 840 at a fork mounting pivot 630. The fork mountingpivot 830 may provide an axis of rotation for the entire load wheelassembly 800 relative to the fork.

The first load arm 810 may rotate about the axis of rotation formed byfork mounting pin 830 b, and the load wheel may be rotationally coupledto an end of the first load arm 810 opposite from the axis of rotation.For example, the load wheel may be rotationally coupled to the firstload arm 810 at a load wheel axis 845. The load wheel may support thefork at an elevation above the load wheel. In some embodiments, thefirst load arm 810 may be associated with a first angle of incidencethat passes through the centerlines of the fork mounting pin 830 and theload wheel axis 845.

The second load arm 840 may be pivotally coupled to the first load arm810 at the axis of rotation formed by the fork mounting pin 830 b. Insome embodiments, the second load arm 840 may be associated with asecond angle of incidence that passes through the centerlines of thefork mounting pin 830 and an aperture 850 for a pull rod pin.Additionally, a load arm angle may be understood as being formed betweenthe first angle of incidence associated with the first load arm 810 andthe second angle of incidence associated with the second load arm 840.

In some embodiments, the pull rod may be pivotally coupled to the secondload arm 840 at the pull rod pin aperture 850. In some example modes ofoperation, the pull rod may change the elevation of the fork above theload wheel without varying the load arm angle.

The mounting pin 830 b may be understood as providing an axis ofrotation that passes through one or more aligned connection holes formedin the first load arm 810 and through one or more connection holesformed in the second load arm 840. The mounting pin 830 b may pivotallycouple the load wheel assembly 800 to the fork.

The adjustment mechanism 870 may be understood as coupling the secondload arm 840 to the first load arm 810. Additionally, the adjustmentmechanism 870 may vary the load arm angle formed between the first loadarm 810 and the second load arm 840 to adjust the elevation of the forkabove the load wheel. For example, the adjustment mechanism 870 mayinclude a threaded shaft 870 b, in which a rotation of the threadedshaft 870 b may operate to vary the load arm angle.

The adjustment mechanism 870 may include an adjustable mountingstructure 820 pivotably coupled to the second load arm 810 at pivotpoints 822 by a pair of load pins 825 a, 825 b. The adjustable mountingstructure 820 may be translatable along the axis of the threaded shaft870 b, causing the first load arm to pivot about the load pins 825 a,825 b. The adjustable mounting structure 820 may include a through-hole875 into which the threaded shaft 870 may be variably inserted to varythe load arm angle.

FIGS. 11A-D illustrate several views of another embodiment of anadjustable load wheel assembly, including a perspective view (FIG. 11A),a top view (FIG. 11B), and side view (FIG. 11C), and an exploded view(FIG, 11D), in accordance with various embodiments. The adjustable loadwheel assembly 900 may include a load arm 910 pivotably coupled to forkat a fork mounting pivot 930. The fork mounting pivot 930 may provide anaxis of rotation for the entire adjustable load wheel assembly 900relative to the fork. One or more pull rods may be pivotably coupled tothe load arm 910 at pull rod aperture 950. Actuation of the pull rod maycause the adjustable load wheel assembly 900 to pivot about forkmounting point 930.

The load arm 910 may be pivotably coupled to a wheel assembly thatincludes first and second pivot brackets 940 a, 940 b, a fixed wheel942, and an adjustable wheel 944. In various embodiments, first andsecond pivot brackets 940 a, 940 b may couple to the load arm 910 atpivot bracket mounting aperture 940 c. First and second pivot brackets940 a, 940 b may, in turn, each rotationally couple to two load wheels:a fixed load wheel 942 and an adjustable load wheel 944. The fixed loadwheel 942 may include a hub defining an axis that passed through thegeometric center of the fixed load wheel. The fixed load wheel 942 maybe rotationally disposed on a fixed axle that couples to the first andsecond pivot brackets 940 a, 940 b near the ends of the first and secondpivot brackets 940 a, 940 b that are positioned closer to the load arm910.

An adjustable load wheel 944 having an eccentric hub (e.g., one thatdoes not pass through the geometric center of the adjustable loadwheel), may be disposed on a drive axle 948 near the ends of first andsecond pivot brackets 940 a, 940 b that are farther from the load arm910. In various embodiments, the adjustable load wheel 944 may bereleasably coupled to the first and second pivot brackets 940 a, 940 bby a drive axle 948 and secured with a nut 946. In various embodiments,because of the eccentric hub of the adjustable load wheel, changing theorientation of the eccentricity with respect to the load arm 910 mayalter a distance between the drive axle 948 and the operating surface.

Thus, disclosed in some embodiments are load wheel assemblies for pallettrucks, comprising: a load arm that is rotatable about an axis ofrotation, wherein the load arm has a first end that pivotably couples toat least one pull rod and a second end opposite the first end thatpivotably couples to a wheel assembly comprising a fixed wheel and anadjustable wheel. In various embodiments, the wheel assembly may furthercomprise first and second pivot brackets pivotably disposed at oradjacent to the second end of the load arm. In various embodiment, eachof the first and second pivot brackets may have a first end that extendstoward the load arm and a second end, opposite the first end, extendingaway from the load arm.

In various embodiments, the fixed wheel may be rotatably disposedbetween the respective first ends of the first and second pivotbrackets. In various embodiments, the adjustable wheel may be rotatablydisposed between the respective second ends of the first and secondpivot brackets. In various embodiments, the fixed wheel may have a hubthat is disposed through the geometric center of the fixed wheel. Theadjustable wheel may have an eccentric hub. The orientation of theeccentric hub may be adjusted by a user to adjust the distance betweenthe load arm and the operating surface. Actuation of the pull rod maycause the load arm to pivot about the axis of rotation.

The orientation of the eccentric hub may be controlled by the positionof the drive axle 948. Thus, the distance between the drive axle 948 andthe operating surface may be adjusted by loosening the nut 946, rotatingthe drive axle 948 to a desired position in the first and second pivotbrackets, and re-securing the nut 946 to fix the drive axle 948 in adesired position. In so doing, the position of the eccentric hub may becontrolled and the position of the outer surface of the adjustable loadwheel 944 relative to the operating surface may be controlled withprecision. FIG. 10 illustrates an example process 1000 of operating aload wheel assembly that includes an adjustable linkage system. Atoperation 1010, a pallet truck may be located on a flat operatingsurface. The pallet truck may include a first fork and a second fork.

At operation 1020, a first pull rod may be pulled to raise the firstfork from a lowered position to a raised position.

At operation 1030, a second pull rod may be pulled to raise the secondfork from a second lowered position to a second raised position. In someexamples, an elevation of the first fork relative to the operatingsurface may be different than a second elevation of the second forkrelative to the operating surface in one or both of the raised orlowered operating positions.

At operation 1040, via an adjustment mechanism operably coupled to boththe first pull rod and a first load wheel at least partially housedwithin the first fork, a height of the first load wheel may be adjustedrelative to the operating surface without changing the elevation of thefirst fork. The height of the first load wheel may be varied byadjusting a distance between the first load wheel and the first forkwithout pulling the first pull rod.

The adjustment mechanism may include a rotational adjustment device, andthe height of the first load wheel may be adjusted by rotating therotational adjustment device in a first rotational orientation toincrease the height of the first load wheel relative to the operatingsurface. Additionally, the rotational adjustment device may be rotatedin a second rotational orientation to decrease the height of the firstload wheel relative to the operating surface.

In some embodiments, the process 1000 may further include lowering boththe first fork and the second fork, and the height of the first loadwheel relative to the operating surface may be adjusted with the firstfork in the lowered position. In other embodiments, the first pull rodand the second first pull rod may be pulled at the same time, and theheight of the first load wheel relative to the operating surface may beadjusted after the first and second pull rods have both been pulled,with the first fork and second fork located in the raised position.

A second load wheel may be at least partially housed within the secondfork, and the distance between the first load wheel and the first forkmay be adjusted while a second distance between the second load wheeland the second fork remains fixed.

An adjustable load wheel assembly may allow the manufacturer, dealer,customer, operator or other use to fine-tune or “dial” in the adjustmentto the load wheel elevation/attitude on the assembly line or in thefield, such as to accommodate possibly uneven load wheel wear duringoperation of the pallet truck. Additionally, manufacturing tolerancesmay be relaxed somewhat, since error adjustment may be resolved afterthe manufacturing and/or assembly process, via the load wheel adjustmentmechanism.

Although certain embodiments have been illustrated and described herein,it will be appreciated by those of ordinary skill in the art that a widevariety of alternate and/or equivalent embodiments or implementationscalculated to achieve the same purposes may be substituted for theembodiments shown and described without departing from the scope. Thosewith skill in the art will readily appreciate that embodiments may beimplemented in a very wide variety of ways. This application is intendedto cover any adaptations or variations of the embodiments discussedherein. Therefore, it is manifestly intended that embodiments be limitedonly by the claims and the equivalents thereof.

What is claimed is:
 1. A load wheel assembly for a pallet truck,comprising: a first load arm that is rotatable about an axis ofrotation; a load wheel rotationally coupled to an end of the first loadarm opposite from the axis of rotation, wherein the load wheel supportsa fork at an elevation above the load wheel; a second load arm pivotallycoupled to the first load arm at the axis of rotation and forming a loadarm angle; and an adjustment mechanism further coupling the second loadarm to the first load arm, wherein the adjustment mechanism varies theload arm angle formed between the first load arm and the second load armto adjust the elevation of the fork above the load wheel.
 2. The loadwheel assembly of claim 1, wherein the axis of rotation is provided by amounting pin that passes through aligned connection holes formed in thefirst load arm and the second load arm, and wherein the mounting pinpivotally couples the load wheel assembly to the fork.
 3. The load wheelassembly of claim 2, further comprising a pull rod pivotally coupled tothe second load arm, wherein the pull rod changes the elevation of thefork above the load wheel without varying the load arm angle.
 4. Theload wheel assembly of claim 1, wherein the adjustment mechanismcomprises a threaded shaft, and wherein a rotation of the threaded shaftvaries the load arm angle.
 5. The load wheel assembly of claim 4,further comprising an attachment pin coupled to the first load arm,wherein the threaded shaft operably couples the attachment pin to thesecond load arm.
 6. The load wheel assembly of claim 5, wherein theattachment pin is coupled to the first load arm at a positionintermediate the load wheel and the axis of rotation, and wherein theattachment pin comprises a through-hole centrally located in theattachment pin into which the threaded shaft is inserted.
 7. The loadwheel assembly of claim 6, wherein the adjustment mechanism furthercomprises an adjustable mounting structure pivotally coupled to an endof the second load arm opposite the axis of rotation.
 8. The load wheelassembly of claim 7, further comprising a pull rod pivotally coupled tothe second load arm by a pull rod pin, wherein the adjustable mountingstructure is also pivotally coupled to the second load arm by the pullrod pin.
 9. The load wheel assembly of claim 7, wherein the adjustablemounting structure comprises a through-hole into which the threadedshaft is variably inserted to vary the load arm angle.
 10. The loadwheel assembly of claim 9, further comprising a threaded adjustment nutthat maintains an insertion depth of the threaded shaft into thethrough-hole after the elevation of the fork above the load wheel isadjusted.
 11. A method, comprising: locating a pallet truck on a flatoperating surface, wherein the pallet truck comprises a first fork and asecond fork, and wherein an elevation of the first fork relative to theoperating surface is different than a second elevation of the secondfork relative to the operating surface; pulling a first pull rod toraise the first fork from a lowered position to a raised position;pulling a second pull rod to raise the second fork from a second loweredposition to a second raised position; and via an adjustment mechanismoperably coupled to both the first pull rod and a first load wheel atleast partially housed within the first fork, adjusting a height of thefirst load wheel relative to the operating surface without changing theelevation of the first fork.
 12. The method of claim 11, furthercomprising lowering both the first fork and the second fork, wherein theheight of the first load wheel relative to the operating surface isadjusted with the first fork in the lowered position.
 13. The method ofclaim 11, wherein the first pull rod and the second first pull rod arepulled at the same time, and wherein the height of the first load wheelrelative to the operating surface is adjusted with the first fork in theraised position.
 14. The method of claim 11, wherein adjusting theheight of the first load wheel comprises adjusting a distance betweenthe first load wheel and the first fork without pulling the first pullrod.
 15. The method of claim 14, wherein a second load wheel is at leastpartially housed within the second fork, and wherein the distancebetween the first load wheel and the first fork is adjusted while asecond distance between the second load wheel and the second forkremains fixed.
 16. The method of claim 11, wherein the adjustmentmechanism comprises a rotational adjustment device, and whereinadjusting the height of the first load wheel comprises: rotating therotational adjustment device in a first rotational orientation toincrease the height of the first load wheel relative to the operatingsurface; and rotating the rotational adjustment device in a secondrotational orientation to decrease the height of the first load wheelrelative to the operating surface.
 17. The method of claim 16, whereinthe rotational adjustment device comprises a threaded shaft.
 18. Themethod of claim 16, wherein the rotational adjustment device comprises athreaded nut.
 19. The method of claim 18, wherein the adjustablemounting structure further comprises a threaded shaft variably insertedinto a through-hole of the threaded nut, and wherein the method furthercomprises securing, with the threaded nut, an insertion depth of thethreaded shaft into the through-hole after the height of the first loadwheel relative to the operating surface is adjusted.
 20. An apparatusfor adjusting a fork height for a pallet truck comprising a first forkand a second fork, wherein a first load wheel is at least partiallyhoused within the first fork, wherein a second load wheel is at leastpartially housed within the second fork, wherein an elevation of thefirst fork relative to the operating surface is different than a secondelevation of the second fork relative to an operating surface on whichthe pallet truck is located, and wherein the apparatus comprises: meansfor pulling a first pull rod to raise the first fork from a loweredposition to a raised position relative to the operating surface; meansfor pulling a second pull rod to raise the second fork from a secondlowered position to a second raised position relative to the operatingsurface; and means for adjusting a distance between the first load wheeland the first fork without changing the elevation of the first fork.